This 84-year-old, seven-story apartment building required extensive rehabilitation of its existing built-up roof (BUR) due to water infiltration affecting top-floor units and deteriorated brick masonry penthouse façades. CSG was retained to oversee the replacement of the roof and its underlying components to halt further water intrusion. In addition, CSG designed modifications and repairs to stabilize and restore the roof-related façade elements. The project presented  challenges, as compliance with current DC Energy Code required increased thermal performance to achieve R-33. Our design addressed this insulation requirement by including the use of an innovative, vacuum-packed insulation that allowed the building to avoid the costly expense of modifying the structure to accommodate typical insulation thicknesses.